The primary purposes of the present research are to refine the engineering of a new merger between the helping professions and technology, the Digital Therapist, and to conduct systematic studies of its clinical efficacy. The Digital Therapist is a modified tape recorder that is capable of signalling patients throughout the day and providing them with messages from their therapists. The messages could include reminders of important goals or motivators, encouragement to use constructive thinking, and useful insight. The engineering goals for this phase of the project are to produce 50 pre-production prototypes that are lighter, smaller, more versatile, and easier to program than the Phase I prototypes. The clinical goals include two large scale studies which will test the extent to which the Digital Therapist can enhance the efficacy of state-of-the-art cognitive-behavioral treatments for obesity and smoking addiction. The studies will include comparison and control groups and measures of the processes (e.g., mood) and outcomes (e.g., weight reduction). If the Digital Therapist proves as effective and versatile as the Phase I evidence suggested, many of the hundreds of thousands of therapists and counselors should become interested in purchasing one.